Specifications

Best Practices for Virtualizing and Managing Exchange 2013

With MPIO, Windows Server 2012 efficiently manages up to 32 paths between storage devices and the

Windows host operating system, and provides fault-tolerant connectivity to storage. Further, as more data

is consolidated on SANs, the potential loss of access to storage resources is unacceptable. To mitigate this

risk, high availability solutions like MPIO have become a requirement.

MPIO provides the logical facility for routing I/O over redundant hardware paths connecting servers to

storage. These redundant hardware paths are composed of components such as cabling, HBAs, switches,

storage controllers, and possibly even power. MPIO solutions logically manage these redundant

connections so that I/O requests can be rerouted if a component along one path fails. The MPIO software

supports the ability to balance I/O workloads without administrator intervention. MPIO determines which

paths to a device are in an active state and can be used for load balancing. Each vendor’s load balancing

policy setting is set in the DSM. (Individual policy settings may use any of several algorithms—such as

Round Robin, Least Queue Depth, Weighted Path, and Least Blocks—or a vendor-unique algorithm.) This

policy setting determines how I/O requests are actually routed.

Best Practices and Recommendations

To determine which DSM to use with existing storage, it is important to check with the storage

array manufacturer. Multipath solutions are supported as long as a DSM is implemented in line with

logo requirements for MPIO. Most multipath solutions for Windows use the MPIO architecture and

a DSM provided by the storage array manufacturer. Use the Microsoft DSM provided in Windows

Server only if it is also supported by the storage array manufacturer, in lieu of the manufacturer

providing its own DSM.

A DSM from the storage array manufacturer may provide additional value beyond the

implementation of the Microsoft DSM because the software typically provides auto-configuration,

heuristics for specific storage arrays, statistical analysis, and integrated management. We

recommend that you use the DSM provided by the storage array manufacturer to achieve optimal

performance. This is because storage array manufacturers can make more advanced path decisions

in their DSMs that are specific to their arrays, which may result in quicker path failover times.

Offloaded Data Transfer

Offloaded Data Transfer (ODX) in Windows Server 2012 enables customers who have invested in storage

technologies such as iSCSI or FC SANs to accomplish more with existing external storage arrays. This is

because ODX lets you quickly move large files and virtual machines directly between storage arrays, which

reduces host CPU and network resource consumption.

ODX enables rapid provisioning and migration of virtual machines and provides significantly faster

transfers of large files, such as database or video files. By offloading the file transfer to the storage array,

ODX minimizes latencies; maximizes the use of array throughput; and reduces host resource usage, such

as CPU and network consumption. File transfers are automatically and transparently offloaded when you

move or copy files, regardless of whether you perform drag-and-drop operations in Windows Explorer or

use command-line file copy commands. No administrator setup or intervention is needed.